Re: possible bug in find_get_pages

[mark gross <mgross@linux.intel.com>]

On Fri, Mar 06, 2009 at 02:28:50PM -0500, Christoph Lameter wrote:
> On Fri, 6 Mar 2009, mark gross wrote:
> 
> > It seems that page->_count == 0 at some point on some overnight runs
> > with locks the system into a tight loop from the repeat: and a goto
> > repeat in find_get_pages.
> 
> A page with ref count zero should not be in any mapping. If the page is in
> a mapping then the page is used. Therefore the refcount should be > 0.
> 
> If there is a page with zero refcount and its in a mapping then something
> erroneously decreased the refcount.
> 
> Nick wrote the code so I CCed him.

thanks!  This is on early hardware so perhaps there isn't anything to
see here.  

Still form a static read of the code that goto repeat raises
eyebrows as why would anyone expect to get anything different from
radix_page_deref_slot calling it again with the same arguments?

--mgross

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